Improvement in steam-boilers



UNITED STATES PATENT OFFICE.

WILLIAM HOPKINS, OF DUBUQUE, IOWA.

IM PROVEMENT IN STEAM-BOILERS.

Specification forming part of Letters Patent No. 213,422, dated March 18, 1879; application filed December 26, 1878.

obtain a perfect circulation of the water and perfect and economical combustion of fuel.

My invention consists in a steam boiler or generator having an annular waterspace formed by vertical concentric shells, and an inner box or water-space through which the tubular flues pass. The inner and outer water-spaces are connected at intervals near the top and at thebottom by tubespassing through the combustion-chamber, and the products of combustion have free passage between the two Water-spaces.

In the accompanying drawings, Figure 1 is a vertical section of my improved boiler. Fig. 2 is a sectional plan on line as m. Fig. 3 is a sectional plan on line y 3 Similar letters of reference indicate corresponding parts.

A is the boiler, of which a is the fire-space; b, the grate-bars; c, the fire-door; d, the steam-dome, and e'plates in the dome to prevent water rising or priming of the boiler.

f is an outer, and 9 an inner, shell made of boiler-iron, the inner shell, g, being somewhat smaller than f, so as to form an annular waterspace, 0, that extends from the base to the upper part of the boiler, where f is enlarged to form the steam-dome. The inner shell, g, is slightly larger in diameter at the bottom, and above the water-line is formed with coni cal sides, and terminates in the smoke-pipe h. The two shells are connected by stay-bolts, as shown.

At the inside of the boiler, above fire-space a, there is a cylindrical shell, c, forming a water-space, D, through which the tubular flues 70 pass vertically. This shellt' is supported by the water-tubes Z, that extend from the under side of '5 around theinside of fire-space ainto the lower part of water-space O. The waterspace D also communicates with space 0 by short screw-tubes m, at intervals around the upper end, and these tubes m serve as an additional means of support for shell 2'. To permit of inserting tubes m after the shellz' is put in place, the outer shell, f, is provided with openings closed by screw-plugs a, opposite to where tubes m are to be screwed in, as shown in Fig. 2, through which openings tubes m may be inserted.

By this construction there is an annular fluespace around shell 2', in addition to flues is, so that when the fire-door is opened the cold air goes up between the shells instead of striking the tubes, thereby avoiding sudden contraction and expansion, which might cause the tubes to leak. The flame and heat may spread around and between the shell, thereby permitting complete mixture of air with the gases, rendering combustion more perfect and giving a large extent of heating-surface.

The circulation will be perfect. 1? p are the water-supply tubes, and the water passing up tubes Z becomes heated before it enters waterspace D. The direction of the circulation is shown by the arrows.

This construction furnishes a very compact and strong boiler, that has a large extent of heating-surface in comparison with its size, and will make steam rapidly.

Having thus described my invention, I claim as new and desire to secure by Letters Pat ent In a steam-boiler, two concentric vertical shells with one water-space between them and another one on the inside, set over the tire, and through which the fire-tubes pass, said water-spaces being connected at top and bottom by tubes passing through the combustionchamber, in combination with a conical outlet for the products of combustion, surrounded by a steam-dome having arch e, as shown and described.

WILLIAM HOPKINS.

Witnesses:

CHAS. B. DEAN, GEo. A. FIFIELD. 

